You'll probably be able to do the same quests and stuff, they might only buff the drop rates for atmas/zodiac/alex items or increase the amount of "lights" you get. They should make it so you only need 1 book/stat after you get your Atmas. However, it kinda helps to populate low level dungeons too. I'm not sure about Alexandrite though. How can you even nerf that? The only thing that comes to my mind, is basically giving you a shit ton of these. The Materia prices will probably drop a lot with the new tier 5 soon to be implemented.